The invention relates to combined shoulder harness/lap belt restraints of the type having a pair of shoulder straps anchored behind the head and extending down over the occupant's shoulders to lower, side anchor points adjacent opposite sides of the seat, and a lap belt extending from one side anchor, across the occupant's lap, and connected to the opposite side anchor.
Restraint apparatus of the foregoing configuration are sometimes called five-point or six-point anchor systems based on the total number of points at which the various shoulder straps and lap belt ends are anchored. In a five-point anchor system, the upper ends of the shoulder straps are merged in an inverted Y configuration and jointly fastened to a single, behind-the-head anchor point, and the lower ends of the shoulder straps are separately anchored to the side anchor points as are the opposite ends of the lap belt, thereby totaling five separate anchor locations. In a six-point anchor system, the shoulder straps are individually connected to separate, behind-the-head anchors, resulting in one additional anchor point over the five-point configuration.
Restraint apparatus of this type have been shown to be more effective, on an overall basis, in reducing the potential for bodily injury under dynamic load conditions associated with a crash impact. For example, five and six-point restraint systems as characterized above, have been found more effective than other common restraints of the combined, shoulder harness and lap belt type such as the bandolier configuration--a lap belt and a single shoulder strap crossing the upper torso; the three-point restraint--a lap belt and two shoulder straps extending from a single behind-the-head anchor and first diverging to pass on opposite sides of the occupant's head and then extending downwardly in a convergent fashion to a center-buckle fastening point at the midpoint of the lap belt; and the four-point restraint--similar to the above three-point system except that the upper ends of the shoulder straps are independently attached to separate, spaced apart anchors located above and behind the occupant's shoulders.
Five and six-point anchor systems have been particularly effective in minimizing the tendency of the occupant's body to submarine (rotation of the pelvis accompanied by slippage of the pelvis region under the lap belt) and in minimizing lumbar compression (axial compression of the spine). It is believed that the effectiveness of this type of restraint is due in part to the independent anchoring of the shoulder straps and lap belt ends so that under dynamic loading each shoulder strap, and the lap belt are held snugly against the occupant's body, without tending to loosen at one restraint location in reaction to an excessive tension load at another strap or belt location.
For example, in certain prior combined shoulder harness and lap belt restraints, the shoulder strap and lap belt portion on each side of the seat are made as one continuous web anchored by a slip fitting to structure on the corresponding side of the seat. Such a system, in reaction to certain impact conditions allows the pelvis to be accelerated against the lap belt in such a manner that the continuous lengths of webbing are pulled through the slip fittings at the sides of the seats, taking slack from the upper portions of the webbing that serve as the shoulder straps. The lap belt is thereby lengthened to a degree that significantly increases the risk of submarining. Conversely. excessive acceleration of the upper part of the occupant's torso places such force on the shoulder straps that some of the webbing is pulled through the slip fittings causing excessive tightening or cinching of the lap belt, which may result in injury to the abdominal or pelvic region of the occupant. Thus, the independent anchoring of the shoulder straps and lap belt ends provided by the five and six-point anchor systems, has proved to be a desirable, and in some cases critically important feature.
While the five and six-point restraints having independent strap and belt anchoring have proven safety advantages when properly worn, this type of restraint configuration, as heretofore constructed, does not lend itself to ease and quickness in donning and removal. Unlike other restraints such as the bandolier and three/four-point systems which can readily accommodate a single-point release, the five and six-point systems have in most applications, required two or more release points, such as provided by a pair of devices at each side anchor for jointly releasing the lower ends of the shoulder straps and the adjacent ends of the lap belt. A single-point release at one side anchor of the five and six-point restraints can be combined with a suitable shoulder strap adjuster for lengthing and cinching the nonreleasing shoulder strap, however, such a configuration has been found difficult to use and for this reason has not been widely adopted. The continuous web type of restraint, which is described above, is, unlike the five and six-point restraints, readily adapted to a single-point release. One buckle located at the center of the lap belt can be released to cast off the lap belt, and at the same time loosen the shoulder straps by virtue of the continuous web and slip fittings at the side anchor points. However, the slip fittings which facilitate the release of the restraint, are the cause of the above-mentioned, undesired interaction between lap belt tension and shoulder strap tension.
The foregoing advantages and disadvantages of the various restraint systems apply with even greater import in the case of restraints used on aircraft. The five and six-point anchor systems, when used for example by flight attendants on commercial aircraft, may be able to reduce the risk of at least certain kinds of bodily injury in the event of a crash. However, the difficulty in donning and escaping from this type of restraint system is a serious drawback when proposed for use by flight attendants, who are usually the last to sit down and secure their restraints, and must be the first to release and shed their restraints for giving aid in the case of an emergency.
Accordingly, an object of the invention is to provide a combined shoulder harness and lap belt restraint that affords optimum protection against bodily injury under crash conditions, and at the same time provides the convenience, ease and safety of a single-point fasten/release feature.
Another object is to provide the above-mentioned single-point fasten/release feature in a combined shoulder harness and lap belt restraint of the five and six-point anchor type system characterized by independent anchoring of the ends of the shoulder straps and lap belt.
An additional object is to provide such a combined shoulder harness and lap belt restraint of the five and six-point anchor type, incorporating the single-point fasten/release feature, and that further has the capability of being quickly arranged in a stowed configuration which enhances the ease and quickness with which the restraint can be donned, particularly under emergency conditions.
Still another object is to provide such a combined shoulder harness and lap belt restraint having one or more of the above advantages, and further provides the capability of being adjustable to an extent that enables the restraint to fit occupants of widely varying size.